DERIVATIVE INSTRUMENTS - Maximum Potential Risk, Fair Value, Weighted-Average Years to Maturity, and Underlying Referenced Credit Obligation Type for Credit Default Swaps (Detail) (Corporate Bonds, USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2012	Dec. 31, 2011
Credit Derivatives [Line Items]
Maximum potential risk	$ (367)	$ (381)
Estimated fair value	(97)	(130)
A
Credit Derivatives [Line Items]
Credit Rating	A	A
Maximum potential risk	(139)	(146)
Estimated fair value	(4)	(17)
BB or Lower
Credit Derivatives [Line Items]
Credit Rating	BB or lower	BB or lower
Maximum potential risk	(228)	(235)
Estimated fair value	(93)	(113)
Less than one year
Credit Derivatives [Line Items]
Maximum potential risk	0	0
Estimated fair value	0	0
Less than one year | A
Credit Derivatives [Line Items]
Maximum potential risk	0	0
Estimated fair value	0	0
Less than one year | BB or Lower
Credit Derivatives [Line Items]
Maximum potential risk	0	0
Estimated fair value	0	0
One to three years
Credit Derivatives [Line Items]
Maximum potential risk	0	0
Estimated fair value	0	0
One to three years | A
Credit Derivatives [Line Items]
Maximum potential risk	0	0
Estimated fair value	0	0
One to three years | BB or Lower
Credit Derivatives [Line Items]
Maximum potential risk	0	0
Estimated fair value	0	0
Three to five years
Credit Derivatives [Line Items]
Maximum potential risk	(139)	(146)
Estimated fair value	(4)	(17)
Three to five years | A
Credit Derivatives [Line Items]
Maximum potential risk	(139)	(146)
Estimated fair value	(4)	(17)
Three to five years | BB or Lower
Credit Derivatives [Line Items]
Maximum potential risk	0	0
Estimated fair value	0	0
More than Five and within Ten Years from Balance Sheet Date
Credit Derivatives [Line Items]
Maximum potential risk	(228)	(235)
Estimated fair value	(93)	(113)
More than Five and within Ten Years from Balance Sheet Date | A
Credit Derivatives [Line Items]
Maximum potential risk	0	0
Estimated fair value	0	0
More than Five and within Ten Years from Balance Sheet Date | BB or Lower
Credit Derivatives [Line Items]
Maximum potential risk	(228)	(235)
Estimated fair value	$ (93)	$ (113)